Use of color histograms to perform image and video analysis for database applications is common place. A histogram is an array of value-versus-count, where “count” contains the number of occurrence of that particular “value”. In the case of image intensity histogram, “value” is the pixel value and “count” is the number of pixels in the image attaining that value. Histograms of separate color channels may also be computed in a similar fashion. Histograms of separate color channels may be concatenated into a single color histogram array. Histograms of DC coefficients of block DCT (Discrete Cosine Transform) of images may also be calculated, where value equals the DC value and count is the number of blocks with the same DC value.
A histogram, or a set of statistics of the histogram, e.g., the first three orders of statistics, are often used as image feature descriptors in analyzing and representing the associated images. In video analysis, histograms are used to compute scene changes, video summaries. In image analysis, color feature of the image is described via its color histogram. In that case, for example, a color image may be represented by nine numbers corresponding to the first three orders of statistics per each color channel histogram, or a set of three histograms themselves. Histograms are often used in image and video analysis. Histogram computation may present a computational bottleneck.
None of the prior art discloses a camera that has on-line computation and storage capability for image histograms, or a system employing such a camera that is capable of quick analysis of image content.
U.S. Pat. No. 4,606,065 to Beg et al. describes an image processing system that includes a ‘histogram mode’ wherein locations in a memory circuit function as sorting bins.
U.S. Pat. No. 4,742,551 to Deering describes a mechanism for computing grey-scale histograms.
U.S. Pat. No. 5,339,166 to LeBrat et al. describes an image classification system based which calculates histograms to determine scene motion.
U.S. Pat. No. 5,521,841 to Arman et al. describes a video browser that is shape-dependent.
U.S. Pat. No. 5,606,655 to Arman et al. describes a method for determining a representative frame taken from a group of frames.
R. L. Lagendijk et al. “Visual Search in A SMASH System,” Proceedings of IEEE ICIP96 Conference, pp. 671-674, Lausanne, Switzerland, 1996.
B. Yeo and B. Liu, “Rapid scene analysis on compressed video,” IEEE Trans. On Circuits and Systems for Video Technology, vol. 5, no. 6, 1995.